The effectiveness of intra-aortic balloon pump (IABP) therapy is dependent on physiological and physical variables, perhaps the most important of which is the setting of IABP timing of inflate and deflate relative to the cardiac cycle. The optimization of timing us currently handled manually, delegated to a pump technician or perfusionist, and is updated anywhere from several times an hour to continuously. The person responsible uses the arterial pressure waveform to monitor performance. Research has shown, however, that there is an optimal time for the beginning of inflation and deflation, and that this time is related to the opening and closing of heart valves. This proposal describes research aimed at developing a system which utilizes phonocardiographic heart sounds S1 and S2 for timing references in the cardiac cycle, and controls and IABP automatically therefrom. The system would use hardware and software to detect S1 and S2 and set the timing of the IABP on a continuous basis, thereby providing superior therapy with a lower requirement for professional intervention. A prototype system will be built and tested in vivo, comparing its timing to that set by an experienced clinician. The ultimate system will be an add- on unit to commercially available balloon pumps.